It is often desirable to provide a visual indication of the level of liquid in a tank such as for rinse aid dispenser tanks which are provided in many dishwashers in order to automatically dispense rinse aid liquids during each rinse cycle.
The dispenser tank holds a volume of rinse liquid sufficient for many rinse cycles such that the user is not required to add the rinse and liquid for each use of the machine. Such tanks are typically located within the dishwasher door so as to not be visible from the exterior of the machine and hence a simple sight glass associated directly with the tank is not practical.
U.S. Pat. No. 3,272,011 to Kent et al discloses one such indicator arrangement in which a visual indication is provided of the level of rinse aid liquid contained within the dispenser tank. The visual indicator is located remotely from the tank and is positioned so as to be easily viewed by the dishwasher user.
This particular indicator arrangement comprises a length of tubing extending upwardly from the tank, and in fluid communication with the lower region of the reservoir tank interior and having a reversely curved helical section, a portion of which is positioned adjacent a viewing window. A quantity of indicator fluid is disposed in the curved tube section, and a pressure developed in the tube section by the presence of liquid in the tank causes a displacement of the indicator liquid in correspondence with the level of liquid in the tank. The system is appropriately calibrated such that upon declining of the liquid level in the tank to a near-empty condition, the indicator liquid retreats in the tube section adjacent the viewing window to thus provide an indication of the empty condition of the reservoir tank.
This arrangement is peculiarly adapted to top-loading dishwashers, but most modern dishwasher designs are of the front-loading type, in which the dishwasher door is mounted to the front of the machine and is opened by being swung downwardly to enable the dishware items to be loaded.
Also, the air column trapped within the tube changes in volume with changes in temperature and barometric pressure conditions, such that a difference in indication will occur with changes in these conditions.
In many such front-loading dishwashers, the tank is mounted in the door itself and subjected to the door swinging movement from the closed (vertical) to the open (horizontal) position.
The Kent et al patent employs an indicator liquid differing from the tank liquid which must be added at assembly of the machine. This, of course, adds to the cost of manufacture since the indicating liquid must be supplied at assembly and a calibrated volume of liquid introduced into the indicator system. It would, of course, be advantageous if the need for special indicator liquid could be obviated and a simplified procedure for adding the liquid to the system employed. Since rinse aid liquids are dyed to be readily visible, such liquid could be employed in a liquid indicating system of the general type as disclosed in the Kent et al patent.
In U.S. Pat. No. 3,152,723 to Perl et al there is disclosed a visual indicator for the rinse aid dispenser tank, which is viewable only from the inside of the door, i.e., only when the dishwasher door is in the open position.
Other systems have been proposed for obtaining an indication of the rinse aid detector tank which is directly associated with the tank itself as in the Perl et al device.
It may be considered more convenient to view such a liquid level indicator with the door in the closed position, or at a higher point on the door than that at which the tank is mounted.
Accordingly, it is an object of the present invention to provide a level indication arrangement incorporating the remote indication capability of the Kent et al device, while adapting the same to a front-loading dishwasher or other application in which the tank is movably mounted to be swung between positions which are vertically tilted with respect to each other.
It is a further object of the present invention to provide an arrangement for insuring that barometric pressure and temperature changes do not affect the performance of the indicator device.
It is yet another object of the present invention to provide a liquid level indicator utilizing liquid in which the indicating liquid employed may be the same liquid which is disposed in the dispenser tank and a calibrated volume of which is added to the indicator system by a relatively simple procedure.
It is a further object of the present invention to provide such a liquid level indicator apparatus which is relatively simple and low in cost to manufacture.